Dietary emulsifiers, such as carboxymethylcellulose (CMC) and polysorbate-80 (P80), induce low-grade inflammation and metabolic syndrome in mice, promoting colitis in those predisposed to the condition. These emulsifiers alter the gut microbiota, increasing pro-inflammatory potential and microbiota encroachment. Germ-free mice and fecal transplants confirmed that microbiota changes are necessary for inflammation and metabolic syndrome. Emulsifiers reduce mucus thickness, increase bacterial adherence, and alter microbiota composition, leading to increased levels of bioactive LPS and flagellin, which promote inflammation and gut permeability. These changes are associated with increased adiposity, metabolic syndrome, and colitis. Emulsifiers also affect metabolic parameters, including glycemic control and increased food intake. The study suggests that dietary emulsifiers may contribute to the rise in obesity and chronic inflammatory diseases, such as IBD and metabolic syndrome, in modern society. The findings highlight the importance of the host-microbiota relationship and the potential role of food additives in disrupting it. The study used various mouse models and techniques, including microbiota transplantation, q-PCR, and 16S rRNA sequencing, to analyze the effects of emulsifiers on the gut microbiota and host health. The results indicate that emulsifiers can alter gut microbiota composition, increase inflammation, and promote metabolic syndrome, emphasizing the need for further research into the impact of dietary additives on human health.Dietary emulsifiers, such as carboxymethylcellulose (CMC) and polysorbate-80 (P80), induce low-grade inflammation and metabolic syndrome in mice, promoting colitis in those predisposed to the condition. These emulsifiers alter the gut microbiota, increasing pro-inflammatory potential and microbiota encroachment. Germ-free mice and fecal transplants confirmed that microbiota changes are necessary for inflammation and metabolic syndrome. Emulsifiers reduce mucus thickness, increase bacterial adherence, and alter microbiota composition, leading to increased levels of bioactive LPS and flagellin, which promote inflammation and gut permeability. These changes are associated with increased adiposity, metabolic syndrome, and colitis. Emulsifiers also affect metabolic parameters, including glycemic control and increased food intake. The study suggests that dietary emulsifiers may contribute to the rise in obesity and chronic inflammatory diseases, such as IBD and metabolic syndrome, in modern society. The findings highlight the importance of the host-microbiota relationship and the potential role of food additives in disrupting it. The study used various mouse models and techniques, including microbiota transplantation, q-PCR, and 16S rRNA sequencing, to analyze the effects of emulsifiers on the gut microbiota and host health. The results indicate that emulsifiers can alter gut microbiota composition, increase inflammation, and promote metabolic syndrome, emphasizing the need for further research into the impact of dietary additives on human health.